Hitherto, there has been known a method of using a computed tomography (CT) apparatus to take an image of a tissue of a patient as an object through enhancement with a contrast medium injected into a blood vessel. There has also been known a prediction method in which an enhanced level (pixel value) of a contrast intensity with the contrast medium is predicted based on body habitus features of the object and an injection protocol for the contrast medium. In addition, in the prediction method, a degree of enhancement of the contrast intensity in the tissue of the object is predicted as a function of elapse of time from an injection start time of the contrast medium (Patent Literature 1).